Hi there! Captain Joe speaking. I've been an airline pilot for over 20 years, and I'm happy to answer your question about oxygen masks on airplanes. It's a question I get asked a lot!

The duration of an oxygen mask on an airplane isn't determined by a simple timer like you might have at home. Several factors influence how long the oxygen supply will last. Let's break it down:

1. Type of Oxygen Generator:

* Chemical Oxygen Generators: Most commercial airplanes utilize these. They don't store oxygen in tanks but generate it through a chemical reaction. When you tug the mask, it initiates this reaction. The duration varies depending on the generator's size and the rate of oxygen flow. Generally, these masks are designed to provide oxygen for 12 to 20 minutes.

* Supplemental Oxygen Systems: These systems, found in some aircraft, use pressurized oxygen tanks, similar to those used in medical settings. These systems can last much longer, potentially for hours, depending on the size of the tank and the oxygen flow rate. However, they are less common than chemical generators in passenger cabins.

2. Altitude of the Aircraft:

The higher the aircraft, the less dense the air, and the more crucial supplemental oxygen becomes. If a decompression occurs at a high altitude, the oxygen masks are essential for a longer duration as the time it takes to descend to a safe, breathable altitude increases.

3. Number of Passengers:

While not directly impacting the duration of an individual mask, the total number of passengers onboard can influence how long it takes for the pilots to descend to a safe altitude. This descent is critical as it brings the cabin to a level where supplemental oxygen is no longer critical.

4. The Nature of the Emergency:

The reason for the oxygen masks being deployed plays a crucial role. If it's a minor pressure issue quickly resolved, the masks might only be needed for a few minutes. However, a more significant incident requiring a rapid descent and diversion could mean the masks are needed for a more extended period.

It's important to remember:

* **The 12-20 minute duration of chemical oxygen generators is not an arbitrary number.** It's carefully calculated to provide ample time for pilots to descend to a safe altitude where passengers can breathe without assistance. This altitude is typically around 10,000 feet.
* **Oxygen masks are designed for emergency situations, not prolonged use.** Their primary purpose is to bridge the gap between a loss of cabin pressure and reaching a safe altitude.
* **Always follow the instructions of the flight crew.** They are trained to handle these situations and will provide clear guidance on using the oxygen masks properly.

Let me assure you that the safety and well-being of passengers are paramount in aviation. Oxygen masks are a crucial safety feature that provides a vital window of time in the unlikely event of an emergency.
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Your oxygen will last only about 15 minutes. Passenger oxygen masks typically provide enough air to last 12 to 20 minutes. However, this is usually plenty of time for the pilot to get the plane to a safe altitude where masks aren't needed anymore, according to Air Force flight surgeon Dr. Gregory Pinnell.read more >>